Tensioning device



April 9, .1963 J. P. BERND TENSIONING DEVICE Filed Aug. 30, 1961 IN V EN TOR.

ted States atent O 3,084,887 TENSIONING DEVItZE Jules P. Bernd, Muskegon, Mich, assignor to Brunswick Corporation, a corporation of Delaware Filed Aug. 30, 1961, Ser. No. 135,073 4 Claims. (Cl. 242-155) This invention relates to a tensioning device for strands and more particularly to a tensioning device for maintaining balanced tension on a plurality of strands traveling in similar or separate paths.

An object of this invention is to provide a new and improved strand tensioning device in which a plurality of strands are maintained with balanced tension utilizing a single drag maintaining device.

At present when handling a plurality of individual strands such as winding thereof onto a spool or onto a form such as a mandrel in manufacturing processes, it has been necessary to have a separate tensioner for each strand in attempting to obtain a constant tension on each strand. This has substantially increased the expense in having to provide a tensioning device for each strand and also increases the space required for such units.

With the device as defined in the previous object of the invention, these problems are overcome by using a single tensioning device for all strands.

A further object of the invention is to provide a tensioning device in which a constant tension is maintained on all the strands even though the strands may have different path lengths and a strand never loses tension in any normal variation of path length in which the tensioning device has a pulley shaft loosely mounting a series of pulleys, there being a pulley for each strand with a spring associated with each pulley, and a retarding device associated with the shaft for applying torque thereto whereby the strands passing over the pulleys initially deflect the springs until such time as the force exerted through the springs exceeds the setting of the retarding device with resultant rotation of the retarding device.

Another object of the invention is to provide a device as defined in the preceding paragraph in which the spring connecting each pulley to the pulley shaft is a torsion spring having several convolutions about the pulley shaft and having one end thereof connected to the shaft and the other end to the pulley whereby the initial pull of the strand causes an initial deflection of the spring until the force applied to the spring equals the setting of the braking device and a further force causes rotation of the pulley shaft with the pulley, as retarded by the braking device, the spring compensating for force tension increases or decreases in the strand by change of deflection thereof.

Further objects and advantages will become apparent from the following detailed description taken in connection with the accompanying drawings in which:

FIGURE 1 is a side elevational view showing the tensioning device location within a work system;

FIGURE 2 is a front elevational view of the tensioning device taken along the line 22 of FIGURE 1, and;

FIGURE 3 is a section view on an enlarged scale taken along the line 33 of FIGURE 2.

While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail an embodiment of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiment illustrated. The scope of the invention will be pointed out in the appended claims.

[Referring to the drawings, a general system embodying the invention is shown in FIGURE 1 in which a plurality ice of strands are supplied from a strand supply source 10 composed of a plurality of strand supply reels. The strands pass to a mechanism 12 for winding thereof which may be in the form of a winding reel or, as shown, a mandril which rotates under power when mounted on a driven turntable. Intermediate the strand supply source 10 and the mechanism 12, a tensioning device is provided to maintain an average balanced tension on the strands even though there may be variations in tension caused by different path lengths of the strands or the like. The tensioning device 14 includes a retarding or braking device 16 for applying a drag. This retarding device provides a constant torque to a shaft regardless of the speed of the shaft rotation. As an example, a device may be a General Electric hysteresis brake such as Model No. CR 9540AA-400AA. In such device, a pair of magnets are movable, one relative to the other, with one being connected to the output shaft and the amount of torque applied to the shaft may be adjusted by controlling the distance between the magnets. The shaft heretofore referred to is indicated at 18 and at one end extends outwardly from the retarding device 16 and is supported by a sleeve 20 mounted on the retarding device. The other end of the shaft is supported in a pillow block 22 by means of a sleeve 24. Intermediate the endsv thereof the shaft loosely mounts a plurality of pulleys 26, each of which has one of the strands wrapped therearound in the passage of the strand from supply reel to the mechanism 12. These strands are indicated at 30 with one being shown in detail in FIGURE 3. It will thus be seen that the shaft 18 constitutes a pulley shaft for the pulleys 26. The pulleys are maintained in spaced relation along the length of the shaft by means of a plurality of torsion springs 28 associated one with each of the pulleys. As shown in FIGURE 3, each of the torsion springs has one end connected to the pulley shaft and the other end to the pulley with there being several convolutions of the spring about the pulley shaft. The springs function to provide a tensioning action which is more fully described in the operation set forth hereinafter.

The operation of the device is as follows. A predetermined amount of torque is set in the retarding means. As each individual filament or strand is pulled it causes rotation of the associated pulley 26 relative to the pulley shaft 24 and a deflection of the associated spring 28 until the force applied to the spring equals the setting of the braking device. Further force causes the pulley motion to be transmitted to the shaft, causing the pulley shaft to overcome the braking device and rotate. Those strands receiving the greatest amount of initial force will be the first to cause the shaft to rotate. As the force applied to the remainder of the strands approaches that applied to the other strands then these remaining strands will tend to take up their share of the work load. At the same time those pulley springs which were originally receiving a greater force will relax slightly due to exerting less pull on the pulley shaft thus resulting in a generally even tension being applied to all strands. If any one strand begins to slacken its pulley spring will tend to unwind, thus maintaining a generally uniform tensional force within that strand, and the other strands and pulley springs will take up the work load in overcoming the torque force which is not taken by that strand. Gradually the spring will unwind to a point where that strand can again assume its proportional amount of the work load in overcoming the torque supplied by the retarding means and balance will be restored to the system. Conversely, if any one strand begins receiving a greater force than the remaining strands it will cause its respective spring, associated with its pulley, to deflect further, thereby absorbing the increase in force. :That strand will then do the greater part of the work of overcoming the drag should be understood therefrom for some modifications.

will be obvious to those skilled in the art.

I claim:

1. A tensioning device for a multiplicity of strands whereby balanced tension is maintained on said strands comprising: a rotatably mounted pulley shaft, a drag device connected to said shaft and adjustable to obtain a predetermined strand tension, and a plurality of strand pulleys loosely mounted on said pulley shaft and in spaced relation along the length of said shaft, each of said pulleys being connected to the shaft by a spring connected between the pulley and the shaft so that the tension of the springs will vary as the pulleys rotate relative to the shaft whereby any individual strand Will be caused to have the same tension as the other strands due to the movement of the pulleys relative to the shaft.

2. A tensioning device for a multiplicity of strands whereby a balanced tension is maintained on said strands comprising, a rotatably mounted pulley shaft, a retarding device connected to said shaft and adjustable to obtain a predetermined strand tension, and a plurality of strand pulleys loosely mounted. along the length of said pulley shaft, each of said pulleys being connected to the shaft by a torsion spring and arranged to have the tension vary therein as the pulley rotates relative to the shaft whereby any individual strand will be caused to have the same tension as the other strands due to the movement of the pulley for said individual strand relative to the shaft.

3. A tensioning device for a multiplicity of strands whereby balanced tension is maintained on said strands comprising, a rotatably mounted pulley shaft, a retarding device connected to said shaft and adjustable to obtain a predetermined strand tension, and a plurality of strand pulleys mounted in spaced relation on said pulley shaft and adapted to have a strand at least partially wrapped therearound, and means for interconnecting the pulleys and the shaft and maintaining the pulleys in spaced relation to apply even tension to the strands comprising a torsion spring for each pulley having several convolutions about the pulley shaft and having one end thereof connected to said shaft and the other end to said pulley, whereby initial pull on the strand causes an initial deflection of. the spring until the force applied to the spring equals the setting of the braking device and a further force causes rotation of the pulley shaft with the pulley, as retarded by the braking device, with the spring compensating for force increases or decreases in the strand by change of deflection thereof.

4. A tensioning device for a multiplicity of strands whereby balanced tension is maintained on said strands comprising, a rotatably mounted pulley shaft, a retarding device connected to said shaft, and a plurality of strand pulleys loosely mounted in spaced relation on said pulley shaft and adapted to have a strand at least partially wrapped therearound, and means for interconnecting the pulleys and the shaft and maintaining the pulleys in spaced relationship along the length of the shaft to apply even tension to the strands comprising a spring for each pulley having one end thereof connected to said shaft and the other'end to said pulley whereby initial pull on the strand causes an'initial deflection of the spring until the force applied to the spring equals the setting of the braking device and a further force causes rotation of the pulley shaft with the pulley, as retarded by the braking device, with the spring compensating for force increase or decrease in the strand by change of deflection thereof.

References Cited in the file of this patent UNITED STATES PATENTS 2,969,204 Spooner Ian. 24, 1961 

1. A TENSIONING DEVICE FOR A MULTIPLICITY OF STRANDS WHEREBY BALANCED TENSION IS MAINTAINED ON SAID STRANDS COMPRISING: A ROTATABLY MOUNTED PULLEY SHAFT, A DRAG DEVICE CONNECTED TO SAID SHAFT AND ADJUSTABLE TO OBTAIN A PREDETERMINED STRAND TENSION, AND A PLURALITY OF STRAND PULLEYS LOOSELY MOUNTED ON SAID PULLEY SHAFT AND IN SPACED RELATION ALONG THE LENGTH OF SAID SHAFT, EACH OF SAID PULLEYS BEING CONNECTED TO THE SHAFT BY A SPRING CONNECTED BETWEEN THE PULLEY AND THE SHAFT SO THAT THE TENSION OF THE SPRINGS WILL VARY AS THE PULLEYS ROTATE RELATIVE TO THE SHAFT WHEREBY ANY INDIVIDUAL STRAND WILL BE CAUSED TO HAVE THE SAME TENSION AS THE OTHER STRANDS DUE TO THE MOVEMENT OF THE PULLEYS RELATIVE TO THE SHAFT. 